GaN MOS-HEMT USING ATOMIC LAYER DEPOSITION Al 2 O 3 AS GATE DIELECTRIC AND SURFACE PASSIVATION

We report on a GaN metal-oxide-semiconductor high electron mobility transistor (MOS-HEMT) using atomic layer deposition (ALD) Al 2 O 3 film as a gate dielectric and for surface passivation simultaneously. Compared to the conventional AlGaN/GaN HEMT of the same design, six order of magnitude smaller gate leakage current and tripled drain current at forward gate bias demonstrate the effectiveness of ALD Al 2 O 3 as a gate dielectric. The high transconductance and high effective two-dimensional electron mobility verify the high-quality of Al 2 O 3/ AlGaN interface with low interface trap density. The Al 2 O 3 passivation effect is also studied by sheet resistance measurement and short pulse drain characterization.